Pentafluoropropane blowing agent-containing resin blend for use in making integral skin foams

ABSTRACT

It has been found that non-chlorinated pentafluoropropane blowing agents may be used alone or in combination with water in flexible integral skin foams. For example, foams prepared from a resin blend incorporating 1,1,1,3,3-pentafluoropropane (HFA-245fa) alone or in combination with water exhibit physical characteristics such as resistance to abrasion and cracking on flex comparable to conventional chlorinated fluorocarbon blown foams. Such foams made using the resin blend of the present invention are suitable for use in many applications including, for example, shoe soles.

FIELD OF THE INVENTION

The present invention relates to integral skin foams and a process forpreparing such foams. More particularly, the invention relates to resinblends containing pentafluoropropane as the sole blowing or with wateras a co-blowing agent which may be used in making integral skin foams.

BACKGROUND OF THE INVENTION

Integral skin foams are well known to those skilled in the art ofpolyurethane foams. Such foams have a cellular interior and a higherdensity microcellular or non-cellular skin. In general, to prepare suchfoams an organic isocyanate is reacted with a substance having at leastone isocyanate reactive group in the presence of a catalyst, blowingagent, and a variety of optional additives. The reaction is carried outin a mold where a higher density skin forms at the interface of thereaction mixture and the relatively cool inner surface of the foam.

Historically, the most common types of blowing agent used in integralskin polyurethane foams have been chlorofluorocarbons (CFCs) orcombinations of CFCs and other blowing agents. However, in view ofrecent mandates calling for a reduction and eventually elimination ofthe use of CFCs, alternatives are considered necessary.

Past methods of preparing integral skin polyurethanes with CFCs as ablowing gent includes G.B. Patent No. 1,209,297, which teaches the useof a combination blowing agent consisting of a CFC and hydrate of anorganic compound which splits off water at temperatures above 40° C.This blowing agent or combination of agents was used in a formulationwith a suitable polyisocyanate, a polyol containing hydroxyl group and acatalyst. This patent discloses that free water in the system leads to askin that is permeated with fine cells, which is undesirable.

Attempts have been made to evaluate the performance of alternate blowingagents to CFCs. In a paper by J. L. R. Clatty and S. J. Harasinentitled, Performance of Alternate Blowing Agents to Chlorofluorocarbonsin RIM Structural and Elastomeric Polyurethane Foams, presented to theAnnual Polyurethane Technical/Marketing Conference, October 1989, theauthors addressed the use of water as a blowing agent for integral skinpolyurethane reaction injection molded systems (RIM). In thisapplication, the water concentration in the system is controlled by theconcentration and type of molecular sieves used. As in the Great Britainpatent discussed previously, the water is not in a free form but boundin some manner. In this instance, the authors state that this process islimited to use in rigid foam systems; and the flexible integral skinformulations may best be served by using HCFCs or HCFC-22 as substitutesfor CFCs.

A recently employed integral skin foam formulation is described in U.S.Pat. No. 5,100,922 to Wada et al. which relates to a method forproducing a molded product of integral skin polyurethane foam. Themethod comprises reacting and curing (1) a high molecular weight polyolcomprising, as the main component, a polyoxyalkylene polyol having, asthe main constituent, oxyalkylene groups of at least 3 carbon atoms andoxyethylene groups at its molecular terminals with the overalloxyethylene group content being not higher than 15% by weight and havinga hydroxyl value of not higher than 80, (2) a crosslinking agentcontaining a compound having an aromatic nucleus and at least two activehydrogen containing groups selected from the group consisting ofhydroxyl groups, primary amino groups and secondary amino groups, and(3) a polyisocyanate, in a mold in the presence of a catalyst and ahydrogen atom containing halogenated hydrocarbon foaming agent. While anextensive list of blowing agents are provided, the only pentafluorocompounds described are chlorinated compounds such as3,3-dichloro-1,1,1,2,2-pentafluoropropane and1,3-dichloro-1,1,2,2,3-pentafluoropropane, which are consideredundesirable.

More recently U.S. Pat. No. 5,506,275, issued to Valoppi, the presentinventor, which relates to the use of 1,1,1,2-tetrafluoroethane as analternative to conventional chlorinated fluorocarbon blowing agents inintegral skin foam formulations. While this patent offers an alternativeto halogenated hydrocarbon blowing agents per se,1,1,2-tetrafluoroethane (HFC-134a) boils at −26.5° C. and thus requiresspecial gas delivery systems to introduce and maintain the blowing agentin solution, especially in warm weather conditions, i.e., above 90° F.As such, still further improvements in the art are considered necessary.

It has been found that foams utilizing pentafluoropropane blowing agentsand, in particular, 1,1,1,3,3-pentafluoropropane as the blowing agentalone or in combination with limited amounts of water can be preparedwhich meet the stringent requirements inherent to integral skin foamapplications such as an acceptable appearance and must exhibit enhancedresistance to abrasion and cracking upon flex. Further, thepentafluoropropane blowing agents utilized in association with thepresent invention are generally soluble in resinous solution thuseliminating or greatly reducing the need for specialized gas deliverysystems to maintain pressure on the system.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a flexible, lowdensity, integral skin polyurethane foam capable of use in variousapplications. The integral skin foam may be made using a resin blendcomprising:

a) an active hydroxy functional polyol composition;

b) a blowing agent including a non-chlorinated pentafluoropropane andoptionally water; and, optionally,

c) a catalyst; and

d) one or more compounds selected from the group consisting essentiallyof chain extenders, a surfactant, an alcohol having from 10 to 20carbons, fillers, pigments, antioxidants, stabilizers and mixturesthereof.

The general process for making such integral skin foams comprisesreacting a polyisocyanate component with an isocyanate reactive compoundin the presence of a catalyst of a type known by those skilled in theart and a non-chlorinated pentafluoropropane blowing agent optionally inassociation with water as a co-blowing agent. A catalyst which assistsin controlling foam formation may be used as well as a surfactant toregulate cell size and structure.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The organic polyisocyanates used in the instant process containaromatically bound isocyanate groups. Representative of the types oforganic polyisocyanates contemplated herein include, for example,1,4-diisocyanatobenzene, 1,3-diisocyanato-o-xylene,1,3-diisocyanato-p-xylene, 1,3-diisocyanato-m-xylene,2,4-diisocyanato-1-nitrobenzene, 2,5-diisocyanato-1-nitrobenzene,m-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluenediisocyanate, mixtures of 2,4- and 2,6-toluene diisocyanate,4,4′-biphenylmethane diisocyanate, 4,4′diphenylmethane diisocyanate,3,3′-4,4′-diphenylmethane diisocyanate, and3,3′-dimethyldiphenylmethane-4,4′-diisocyanate; the triisocyanates suchas 4,4′,4″-triphenylmethane triisocyanate, polymethylene polyphenylenepolyisocyanate, and 2,4,6-toluene triisocyanate; and thetetraisocyanates such as 4,4-dimethyl-2,2′-5′-diphenylmethanetetraisocyanate. Especially useful due to their availability andproperties are 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethanediisocyanate, polymethylene polyphenylene polyisocyanate and mixturesthereof.

These polyisocyanates are prepared by conventional methods known in theart such as the phosgenation of the corresponding organic amine.Included within the usable isocyanates are the modifications of theabove isocyanates which contain carbodiimide, allophanate, alkylene orisocyanurate structures. Quasi-prepolymers may also be employed in theprocess of the subject invention. These quasi-prepolymers are preparedby reacting an excess of organic polyisocyanate or mixtures thereof witha minor amount of an active hydrogen containing compound determined bythe well known Zerewitinoff Test, as described by Kohler in Journal ofthe American Chemical Society, 49, 3181 (1927). These compounds andtheir methods of preparation are well known in the art. The use of anyone specific active hydrogen compound is not critical hereto; rather,any such compound can be employed herein. Generally, thequasi-prepolymers have a free isocyanate content of from 20 percent to40 percent by weight.

Mixtures of polymeric diphenylmethane diisocyanate (polymeric MDI) andcarbodiimide or urethane modified MDI are preferred.

The isocyanate reactive composition, otherwise referred to herein as anactive hydroxy-functional polyol composition may include any suitablepolyoxyalkylene polyether polyol such as those resulting from thepolymerization of a polyhydric alcohol and an alkylene oxide.Representatives of such alcohols may include ethylene glycol, propyleneglycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol,1,4-butanediol, 1,2-pentanediol, 1,4-pentanediols, 1,5-pentanediol,1,6-hexanediol, 1,7-heptanediol, glycerol, 1,1,1-trimethylolpropane,1,1,1-trimethylololethane or 1,2,6-hexanetriol. Any suitable alkyleneoxide may be used such as ethylene oxide, propylene oxide, butyleneoxide, amylene oxide and mixtures of these oxides. The polyoxyalkylenepolyether polyols may be prepared from other starting materials such astetrahydrofuran and alkylene oxide-tetrahydrofuran mixtures,epihalohydrins such as epichlorophydrin, as well as aralkylene oxidessuch as styrene oxide. The polyoxyalkylene polyether polyols may haveeither primary or secondary hydroxyl groups. Included among thepolyether polyols are polyocyethylene glycol, polyoxypropylene glycol,polyoxybutylene glycol, polytetramethylene glycol, block copolymers, forexample, combinations of polyoxypropylene and polyoxyethylene glycols,poly-1,2-oxybutylene and polyoxyethylene glycols and copolymer glycolsprepared from blends or sequential addition of two or more alkyleneoxides. The polyoxyalkylene polyether polyols may be prepared by anyknown process, such as the process disclosed by Wurtz in 1859 andEncyclopedia of Chemical Technology, Vol. 7, pp. 257-262, published byInterscience Publishers, Inc. (1951) or in U.S. Pat. No. 1,922,459.

Other polyoxyalkylene polyether polyols which may be employed are thosewhich contain grafted therein vinylic monomers.

The polyols which have incorporated therein the vinylic polymers may beprepared (1) by the in situ free radical polymerization of anethylenically unsaturated monomer or mixture of monomers in a polyol, or(2) by dispersion in a polyol of a preformed graft polymer prepared byfree radical polymerization in a solvent such as described in U.S. Pat.Nos. 3,931,092; 4,014,846;, 4,093,573 and 4,122,056; the disclosures ofwhich are herein incorporated by reference, or (3) by low temperaturepolymerization in the presence of chain transfer agents. Thesepolymerizations may be carried out at a temperature between 65° C. and170° C., preferably between 75° C. and 135° C.

The amount of ethylenically unsaturated monomer employed in thepolymerization reaction is generally from one percent to 60 percent,preferably from 10 percent to 40 percent, based on the total weight ofthe product. The polymerization occurs at a temperature between about80° C. and 170° C., preferably from 75° C. to 135° C.

The polyols which may be employed in the preparation of the graftpolymer dispersions are well known in the art. Both conventional polyolsessentially free from ethylenic unsaturation such as those described inU.S. Pat. No. RE 28,715 and unsaturated polyols such as those describedin U.S. Pat. No. 3,652,659 and U.S. Pat. No. RE 29,014 may be employedin preparing the graft polymer dispersions used in the instantinvention, the disclosures of which are incorporated by reference.

Representative polyols essentially free from ethylenic unsaturationwhich may be employed are well known in the art. They are often preparedby the catalytic condensation of an alkylene oxide or mixture ofalkylene oxides either simultaneously or sequentially with an organiccompound having at least two active hydrogen atoms such as evidenced byU.S. Pat. Nos. 1,922,459; 3,190,927 and 3,346,557, the disclosures ofwhich are incorporated by reference.

The unsaturated polyols which may be employed for preparation of graftcopolymer dispersions may be prepared by the reaction of anyconventional polyol such as those described above with an organiccompound having both ethylenic unsaturation and a hydroxyl, carboxyl,anhydride, isocyanate, or epoxy group; or they may be prepared byemploying an organic compound having both ethylenic unsaturation and ahydroxyl, carboxyl, anhydride, or epoxy group as a reactant in thepreparation of the conventional polyol. Representative of such organiccompounds include unsaturated mono- and polycarboxylic acids andanhydrides such a maleic acid and anhydride, fumaric acid, crotonic acidand anhydride, propenyl succinic anhydride, and halogenated maleic acidsand anhydrides, unsaturated polyhydric alcohols such as2-butene-1,4-diol, glycerol allyl ether, trimethylopropane allyl ether,pentaerythritol allyl ether, pentaerythritol vinyl ether,pentaerythritol diallyl ether, and 1-butene-3,4-diol, unsaturatedepoxides such as 1-vinycyclohexene monoxide, butadiene monoxide, vinylglycidyl ether, glycidyl methacrylate and 3-allyloxypropylene oxide.

As mentioned above, the graft polymer dispersions used in the inventionare prepared by the in situ polymerization of an ethylenicallyunsaturated monomer or a mixture of ethylenically unsaturated monomer ora mixture of ethylenically unsaturated monomers, either in a solvent orin the above-described polyols. Representative ethylenically unsaturatedmonomers which may be employed in the present invention includebutadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene,styrene, α-methylstyrene, methylstyrene, 2,4-dimethylstyrene,ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene,cyclohexylstyrene, benzylstyrene, and the like; substituted styrenessuch as chlorostyrene, 2,5-dichlorostyrene, bromostyrene, fluorostyrene,trifluoromethylstyrene, iodostyrene, cyanostyrene, nitrostyrene,N,N-dimethylaminostyrene, acetoxystyrene, methyl-4-vinylbenzoate,phenoxystyrene, p-vinyldiphenyl sulfide, p-vinylphenyl phenyloxide, andthe like; the acrylic and substituted acrylic monomers such asacrylonitrile, acrylic acid, methacrylic acid, methylacrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropylmethacrylate, octyl methacrylate, methacrylonitrile, methylα-chloroacrylate, ethyl α-ethoxyacrylate, methyl α-acetam, inoacrylate,butyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, phenylmethacrylate, α-chloroacrylonitrile, methacrylonitrile,N,N-dimethylacrylamide, N,N-dibenzylacrylaminde, N-butylacrylamide,methacryl formamide and the like; the vinyl esters, vinyl ethers, vinylketones, etc., such as vinyl acetate, vinyl chloroacetate, vinylalcohol, vinyl butyrate, isopropenyl acetate, vinyl formate, vinylbutyrate, isopropenyl acetate, vinyl formate vinyl methacrylate, vinylmethoxyacetate, vinyl benzoate, vinyl iodide, vinyltoluene,vinylnaphthalene, vinyl bromide, vinyl fluoride, vinylidene bromide,1-chloro-1-fluoroethylene, vinylidene fluoride, vinyl methyl ether,vinyl other, vinyl propyl ether, vinyl butyl ether, vinyl 2-ethylhexylether, vinyl phenyl ether, vinyl 2-butoxyethyl ether,2,4-dihydro-1,2-pyran, 2-butoxy-2′-vinyloxy diethyl ether, vinyl2-ethylthioethyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinylphenyl ketone, vinyl phosphonates such as bis(β-chloroethyl)vinylphosphonate, vinyl ethyl sulfide, vinyl ethyl sulfone, N-methyl-N-vinylacetamide, N-vinyl pyrrolidene, vinyl imidazole, divinyl sulfide,divinyl sulfoxide, divinyl sulfone, sodium vinylsulfonate, methylvinylsulfonate, N-vinyl pyrrole, and the like; dimethyl fumarate,dimethyl maleate, maleic acid, crotonic acid, fumaric acid, itaconicacid, monomethyl itaconate, butylaminoethyl methacrylate,dimethylaminoethyl methacrylate, glycidyl acrylate, allyl alcohol,glycol monoesters of itacotric acid, dichlorbutadiene, vinyl pyridine,and the like. Any of the known polymerizable monomers can be used, andthe compounds listed above are illustrative and not restrictive of themonomers suitable for use in this invention. Preferably, the monomer isselected from the group consisting of acrylonitrile, styrene, methylmethacrylate, and mixtures thereof.

The total amount of active hydroxy-functional polyol compositionemployed in accordance with the teachings of the present inventionincludes from about 60 pbw to about 100 pbw based on a total of 110parts by weight (pbw) for the resin and a foam index of between about96-104. More preferably the total amount of active hydroxyl-functionalpolyol composition will be from about 65 pbw to about 95 pbw based on atotal parts by weight of the resin of 110.

Illustrative initiators which may be employed for the polymerization ofvinyl monomers are the well known free radical types of vinylpolymerization initiators, for example, the peroxides, persulfates,perborates, percarbonates, azo compounds, etc. including hydrogenperoxide, dibenzoyl peroxide, acetyl peroxide, benzoyl hydroperoxide,t-butyl hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, butyrylperoxide, diisopropylbenzene hydroperoxide, cumeme hydroperoxide,paramenthane hydroperoxide, di-α-cumyl-peroxide, dipropyl peroxide,diisopropyl peroxide, difuroyl peroxide, ditriphenylmethyl peroxide,bis(p-methoxybenzoyl) peroxide, p-monoethoxybenzoyl peroxide, rubeneperoxide, ascaridol, t-butyl peroxybenzoate, diethylperoxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide,n-butyl hydroperoxide, cyclohexyl hydroperoxide, trans-decalinhydroperoxide, α-methylbenzyl hydroperoxide, α-methyl-α-ethyl benzylhydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide,diphenylmethyl hydroperoxide,α,α′-azobis(2-methyl)heptonitrile,1,1-azo-bis(1-cyclohexane)carbonitrile,dimethyl α,α′-azobis(isobutyroitrile), 4,4-′azobis(cyanopetanoic)acid,azobis(isobutyronitrile), 1-t-amylazo-1-cyanocyclohexane,2-t-butylazo-2-cyano-4-methoxy-4-methylpentane,2-t-butylazo-2-cyano-4-methylpentane, 2-(t-butylazo)isobutyronitrile,2-t-butylazo-2-cyanobutane, 1-cyano-1-(t-butylazo)cyclohexane, t-butylperoxy-2-ethylhexanoate, t-butyl perpivalate,2,5-dimethylhexane-2,5-diper-2-ethylhexoate, t-butylperneo-decanoate,t-butyl perbenzoate, t-butyl percrotoate, persuccinic acid, diisopropylperoxydicarbonate and the like; a mixture of initiators may also beused. Photochemically sensitive radical generators may also be employed.Generally from about 0.5 percent to about 10 percent, preferably fromabout 1 percent to about 4 percent, by weight of initiator based on theweight of the monomer will be employed in the final polymerization.

Stabilizers may be employed during the process of making the graftpolymer dispersions. One such example is the stabilizer disclosed inU.S. Pat. No. 4,148,840, which comprises a copolymer having a firstportion composed on an ethylenically unsaturated monomer or mixture ofsuch monomers and a second portio which is a propylene oxide polymer.Other stabilizers which may be employed are the alkylene oxide adductsof copolymers of styrene-allyl alcohol.

The preferred polyols are polyethers having an average functionality ofabout 1.75 to about 3.0 and a molecular weight range of from about 3500to about 5100. The most preferred polyols are polyethers which arecopolymers of ethylene oxide and propylene glycol glycerine ortrimethylolpropane. Include with this group are the previously describedgraft polymer dispersions.

Any suitable catalyst may be used including tertiary amines such astriethylenediamine, N-methylmorpholine, N-ethylmorpholine,diethylethanolamine, N-cocomorpholine,1-methyl-4-dimethylaminoethylpiperazine, methoxypropyldimethylamine,N,N,N′-trimethylisopryl propylenediamine,3-diethylaminopropyldiethylamine, dimethylbenzylamine and the like.Other suitable catalysts are, for example, dibutylin dilaurate,dibutyltin d/acetate, stannous chloride, dibutyltin di-2-ethylhexanoate, stannous oxide, available under the FOMREZ® trademark, aswell as other organometallic compounds such as are disclosed in U.S.Pat. No. 2,846,408.

An alcohol having from about 10 to about 20 carbons or mixtures thereofmay be used in the present invention. Alcohols of this type are known tothose skilled in the art. The types of alcohols contemplated arecommonly produced via the oxo process and are referred to asoxo-alcohols. Examples of some commercially available products includeLIAL 125 from Chemica Augusta Spa or NEODOL® 25 produced by Shell. Suchalcohols are known for enhancing cross-linking, thereby improving tearresistance.

While surface active agents are generally not needed to solubilize theblowing agent of the present invention, in contrast to other knownblowing agents, surface active agents, i.e., surfactants, may beemployed, for example, to regulate the size cell size and structure ofthe resulting foams. Typical examples of such surface active agentsinclude siloxane oxyalkylene heterol polymers and other organicpolysiloxanes, oxyethylated alkyl phenol, oxyethylated fatty alcohols,fluoroaliphatic polymeric esters, paraffin oils, castor oil ester,phthalic acid esters, ricindolic acid ester, and Turkey red oil, as wellas cell regulators such as paraffins.

Chain extending agents which may be employed in the present inventioninclude those having two functional groups bearing active hydrogenatoms. A preferred group of chain extending agents includes ethyleneglycol, diethylene glycol, propylene glycol, dipropylene glycol, or1,4-butanediol and mixtures thereof.

Additives which may be used in the process of the present inventioninclude anti-oxidants, known pigments, such as carbon black, dyes andflame retarding agents (e.g., tris-chloroethyl phosphates or ammoniumphosphate and polyphosphate), stabilizers against aging and weathering,plasticizers, such as gamma butylactone, fungistatic and bacteriostaticsubstances and fillers.

The blowing agent of the present invention includes a non-chlorinatedpentafluoropropane compound and particularly1,1,1,3,3-pentafluoropropane, otherwise known as HFA-245a. Thepentafluoropropane blowing agent is used either alone or in conjunctionwith water in amounts sufficient to provide the desired foam density.Depending upon the amount of water employed as a co-blowing agent andthe pack factor of the molded component, the amount of non-chlorinatedpentafluoropropane blowing agent employed will generally range fromabout 0.5 pbw to about 10 pbw, and more preferably from about 1.0 to 8.0pbw based on a total of 110 parts by weight of the resin for foamshaving molded densities of from 2 pcf to about 40 pcf. By way ofnon-limiting example, the amount of pentafluoropropane used as the soleblowing agent for a shoe sole or the like will generally range fromabout 1.5 pbw to about 5.0 pbw for foams having molded densities of from25 pcf to about 35 pcf at a molded pack factor of 1.5-3.0. By way offurther example, the amount of pentafluoropropane used as a sole blowingagent for a steering wheel will generally range from about 2.0 pbw toabout 8.0 pbw for foams having molded densities of from 25 pcf to about35 pcf with a pack factor of 2.0-6.0. As water is added as a co-blowingagent, the amount of non-chlorinated pentofluoro blowing agent isproportionately reduced. In general, up to about 0.25 pbw of water maybe employed as a co-blowing agent and more preferably between about 0.05pbw to about 0.17 pbw based on a total of 110 parts by weight of theresin.

The mechanical parameters of the instant process are flexible and dependon the final application of the integral skin polyurethane foam. Thereaction system is versatile enough that it may be made in a variety ofdensities and hardnesses. The system may be introduced into a mold in avariety of ways known to those skilled in the art. It may be shot into apreheated closed mold via high pressure injection technique. In thismanner, it processes well enough to fill complex molds at low molddensities (from 19 pcf to 25 pcf). It may also be run using aconventional open mold technique wherein the reaction mixture or systemis poured or injected relatively at low pressure or atmospheric pressureinto a preheated open mold. In the instant process, the system may berun at mold temperatures from about room temperature to about 120° F.with room temperature being preferred.

Having thus described the invention, the following examples are given byway of illustration with all amounts being given in parts by weightunless otherwise indicated.

Density ASTM D-1622 Split Tear ASTM D-1938 Tensile Strength ASTM D-412Graves Tear ASTM D-42 Die C Tensile Elongation ASTM Shore Hardness ASTMD-2240 D-412, Die A Ross Flex ASTM 1052 Taber Abrasion ASTM 1044 PolyolA is a propylene glycol initiated polyoxypropylene poly- oxyethyleneblock copolymer having a hydroxyl number of about 25 and a molecularweight of about 3850. Polyol B is a 31 percent solids, 1:1,acrylonitrile:styrene graft copolymer dispersed, in a trimethylolpropaneinitiated polyoxypropylene-polyoxyethylene block copolymer having amolecular weight of about 4120. The graft polymer dispersion has ahydroxyl number of about 25. Polyol C is a glycerine initiatedpolyoxypropylene-polyoxyethylene block copolymer having a hydroxylnumber of about 27 and a molecular weight of about 5050. XFE-1028 is anamine catalyst comprising a proprietary blend available from AirProducts. T-12 is dibutylin dilaurate. S-25 is an amine catalystcomprising a proprietary blend available from Air Products. WB 3092 is aprepolymer prepared from uretonimine modified isocyanate and propyleneglycol having a free NCO content of 24 wt. % and a viscosity of 120 cpsat 25° C. CFC-11 is 1 fluoro-1,1,1-frichloromethane. HFA-245fa is1,1,1,3,3-pentafluoropropane. HFC-134a is 1,1,1,2-tetrafluoroethane. IsoA is a solvent-free 50/50 weight percent blend of diphenylmethanediisocyanate and a urethane-modified polymethylenepolyphenylpolyisocyanate prepolymer, wherein the blend has an isocyanatecontent of 23 weight percent

TABLE I Foam Formulations 1 2 3 4 5 6 7 8 Component pbw pbw pbw pbw pbwpbw pbw pbw Polyol A 66.8 66.8 66.8 66.8 66.8 66.8 66.8 66.8 Polyol B 2020 20 20 20 20 20 20 Polyol C 7 7 7 7 7 7 7 7 1,4-BDO 6 6 6 6 6 6 6 6 EG0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 XF-E1028 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3T-12 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 S-25 0.02 0.02 0.02 0.020.02 0.02 0.02 0.02 CFC-11 5.2 7.5 HFC-134A 2.1 2.5 HFA-245a 2.7 5.1Water 0.2 0.2 0.2 0.2 0.2 0.2 0.38 0.50 WB 3092 OH #/g 127.1 127.1 127.1127.1 127.1 127.1 138.4 145.5 ISO A 38.78 37.96 39.94 39.78 39.71 38.81ISO B 41.92 44.13

Initially it should be noted that the blowing agent was added inquantities to produce similar free rise densities for all solvent blownfoams to ensure similar pack factors so that the skin thickness iscaused only by the blowing agent condensing on the mold surface. Asshould be understood by those skilled in the art, the phrase pack factoris the ratio of the free rise density to the molded density of theresulting foam.

Resin systems were foamed with the blowing agents being added such thata master batch of resin was produced combining all components except theblowing agent. Karl Fischer method for water determination was performedand residual water was determined to be 0.20%. This value was used todetermine all resin/prepolymer ratios. The liquid blowing agents (CFC-11and HFA-245fa) were added to the resin system and then mixed. Blowingagent was added until a constant amount of blowing agent was obtainedafter mixing. Gaseous blowing agent (HFC-134a) was added to 2000 g ofresin via a gas dispersion tube (20C Pyrex) from a pressurized cylinder(supplied by DuPont) equipped with a gas regulator. The resin wascharged to a round bottom 3-neck flask. The resin was kept cool byplacing the flask in an ice water bath while addition took place so thathigher levels of HFC-134a could be added before saturation. A metal stirshaft connected to a motor kept the resin stirring at approximately 500rpm. The third arm of the round bottom was connected to a cold fingerwith dry ice/isopropyl alcohol mixture for reflux of blowing agent. Thecold finger was equipped with a bubbler to regulate the flow of gas. Theaddition was timed and final weight of blowing agent obtained bymeasuring the change in weight of the flask. A total percentage ofblowing agent in the resin was then calculated. Water was also tested asa blowing agent by adding it directly to the resin and a Karl Fisherwater determination was performed.

Each of the resin blowing agent compositions were added directly into aquart Lily cup for foaming. Enough of the resin/blowing agentcomposition was added to produce foam which flowed over the lip of thequart cup so that free rise densities could be measured. The appropriateamount of prepolymer was weighed directly into the Lily cup. The mixturewas then stirred for 7 seconds with a Vorath 3½″ mix blade at 2000 rpm.Foam cream, gel, top of cup, rise and tack free times were noted. Thenet weight of the foam produced was taken and foam density calculated:g×0.059=lb/ft³. The resultant free rise densities and reactivityprofiles are given in TABLE II.

TABLE II Reactivities and Free Rise Densities 3 4 5 6 1 2 HFC- HFC- HFA-HFA- 7 8 Blowing Agent CFC-11 CFC-11 134a 134a 245fa 245fa Water WaterCream Time 18 15 11 12 15 12 17 15 Gel Time 33 25 21 24 26 29 30 25 Topof Cup 44 48 30 25 32 32 49 30 Rise Time 86 70 81 71 61 61 63 58 TackFree 59 65 60 64 48 59 44 43 Free Rise 12.8 9.4 12.4 9.4 12.6 8.9 16.512.5 Density

The foam components were weighed so that the final total weight is equalto the weight needed in the mold plus approximately 50 g hang-up in theLily cup. The desired plaque molded density was 30 lb/ft³ (0.48 g/cc).After stirring, the foam was poured into a 12″×6″×⅜″ aluminum moldheated to 120° F. which has been sprayed lightly with silicone moldrelease. After 4 minutes, the plaque was demolded and trimmed. The netweight of the plaque was taken and foam density calculated (g/442cc=g/ml). After 1 week curing time, physical properties were tested asreported in Table III below.

As demonstrated in Table III, the cream time of HFA-245fa is slightlyfaster than CFC-11 but not quite as fast as R-134a. This is probablybecause the boiling point of HFA-245fa is in between that of CFC-11 andHFC-134a. Because of the volatility, HFA-245fa (b.p.=15.3° C.) escapesfaster from the resin than CFC-11 (b.p.=23.8° C.) but not as fast asHFC-134a (b.p.=26.5° C.). It may be deduced that HFA-245fa is thereforemore soluble in the resin matrix than HFC-134a but not quite as solubleas CFC-11. Solubility studies were not carried out due to limitedavailability of HFA-245fa. The reported cream time of HFC-134a is notthe actual cream but a frothing of the resin caused by the blowing agentboiling out. It is believed that the slightly faster cream of HFA-245facompared with CFC-11 is due to the same boiling out effect but to a muchlesser extent than HFC-134a.

On a molar basis, HFA-245fa appears to be a more efficient blowing agentthan CFC-11. At the lower free rise density (9 lb/ft³), HFA-245fa is notas efficient a blowing agent as HFC-134a but is equally efficient ablowing agent as HFC-134a at the higher free rise density of 12.5lb/ft³.

When comparing the parts of blowing agent needed to produce a desiredfree rise density, HFA-245fa is a more efficient blowing agent thanCFC-11 at both 9.0 and 12.5 lb/ft³ densities. When comparing blowingefficiency with HFC-134a, it can be seen that more blowing agent isrequired for both 9.0 lb/ft³ and 12.5 lb/ft³. However, the costassociated with the added volume is believed to be more than offset byeliminating the need for specialized transfer and storage equipment,especially at higher temperatures.

At the higher free rise density, namely 12.5 lb/ft³, HFA-245fa producedfoam with superior tensile strength and tear strength to the HFC-134ablown foams (see TABLE III). The HFA-245fa blown foam properties areonly slightly lower than those of CFC-11 blown foams with the exceptionof lower elongations and abrasion resistance. The abrasion resistancefor the HFA-245fa foam (104 mg loss) is still well under the industrystandard of less than 200 mg loss. It is believed that the slightlylower Ross Flex modulus at this free rise density is not indicative ofpoorer flex properties but instead due to a split in the hand mix foam.

At 9 lb/ft³ free rise density, tensile and elongations are superior tothose of the CFC-11 blown foams and all other physical properties areequal. Again, the properties of the HFA-245fa blown foam are farsuperior to that of the HFC-134a blown foam. The hardness of HFA-245fablown foams is similar to that of CFC-11 blown foams. Foams blown withHFC-134a tend to be softer.

As expected, all solvent blowing agents produced foams with superiorphysical properties to those of water blown foams. This is especiallyevidenced in tear strength. The water blown foams used for comparisonhad free rise densities of 16.5 lb/ft³ and 12.5 lb/ft³, respectively.The higher free rise density (16.5 lb/ft³) was used due to ease inhandling and does not flash out of the mold or produce flow lines onfinal parts. The lower free rise density (12.5 lb/ft³) was used ascomparison since the greatest pack factor could be obtained in a waterblown formulation.

Foams blown with HFC-245fa produce a well-defined thick skin asdetermined by Scanning Electron Microscopy (SEM). Skin thicknesses werenot quantitatively measured due to the high variability in skinformation of hand mix plaques. It can be seen in comparison that at both9 lb/ft³ and 12.5 lb/ft³ free rise density, HFC-245fa blown foamsexhibit skin thicknesses about equal to that of CFC-11 blown foams.HFC-245fa produced skins far superior to those foams blown withHFC-134a. Due to its high volatility, HFC-134a does not produce athick-skinned foam. As expected, water exhibited very little true skinsince no condensation is taking place at the mold surface.

When used in an integral skin system, HFC-245fa produces foam withsuperior physical properties and skin thickness to foams blown withHFC-134a. When comparing the HFC-245fa blown foams to foams blown withCFC-11, HFC-245fa produced foams which rival CFC-11 blown foams in bothphysical properties and skin thickness. In practice, the use ofHFC-245fa is believed to be an improvement over HFC-134a, since it iseasier to handle, does not require special gas handling equipment, andproduces foam with excellent physical properties and skin thickness.Further, foams employing HFC-245fa as a blowing agent, and particularlyintegral skin foams, can be used to form articles having a relativelybroad molded density, i.e., from about 2.0 pcf to about 40.0 pcf.

While it will be apparent that the preferred embodiments of theinvention disclosed are well calculated to fulfill the objects stated,it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the spiritthereof.

What is claimed is:
 1. A resin useful in the production of polyurethanefoams having an integral skin layer consisting essentially of: a) anactive hydroxyl functional polyol composition comprising one or morepolyols wherein each of said polyols has a molecular weight of betweenabout 3,500 and about 5,100 and an average functionality of from 1.75 to3.0; b) a blowing agent consisting essentially of1,1,1,3,3-pentafluoropropane and optionally water; c) a catalyst; d) atleast one oxo-alcohol of from C₁₀ to C₂₀; and e) optionally one or morecompounds selected from the group consisting of chain extenders, asurfactant, fillers, pigments, antioxidants, stabilizers and mixturesthereof.
 2. The resin of claim 1 wherein said 1,1,1,3,3pentafluoropropane is present in an amount of from about 0.5 parts byweight to about 10.0 parts by weight based on 110 parts by weight ofa)-d).
 3. The resin of claim 1 wherein said blowing agent includes waterin an amount of from about 0.05 parts by weight to about 0.17 parts byweight based on 110 parts by weight of a)-d).
 4. The resin of claim 1wherein said active hydroxy functional polyol composition is selectedfrom the group consisting of polyoxyalkylene polyether polyols, vinylpolymer grafted polyoxyalkylene polyether dispersions and mixturesthereof.
 5. The resin of claim 1 wherein said active hydroxy-functionalpolyol composition is present in an amount from about 50.0 parts byweight to about 95.0 parts by weight based on 110 parts by weight ofa)-d).
 6. The resin of claim 1 wherein said chain extender is selectedfrom the group consisting of ethylene glycol, diethylene glycol,propylene glycol, dipropylene glycol, butanediol and mixtures thereof.7. The resin of claim 1 wherein said alcohol containing from 10 to 20carbons is an aliphatic alcohol.